Evolving National Practice Patterns of Hypofractionated Stereotactic Radiation Therapy Versus Single-Fraction Radiosurgery for Brain Metastases

Abstract

Single-fraction stereotactic radiosurgery (SF-SRS) has been increasingly utilized in the treatment of patients with brain metastases, but the national uptake of hypofractionated stereotactic radiotherapy (HF-SRT) is unknown. We sought to characterize the evolution of practice patterns of HF-SRT in relation to SF-SRS in the United States over the past decade. The National Cancer Database was used to identify patients with breast cancer, non-small cell lung cancer (NSCLC), colorectal cancer, melanoma, and prostate cancer diagnosed in 2004-2014 who underwent either SF-SRS or HF-SRT to the brain. SF-SRS was defined as radiotherapy dose ≥15 Gy in 1 fraction, while HF-SRT was defined as radiotherapy dose ≥21 Gy in 3 fractions, ≥24 Gy in 4 fractions, or ≥25 Gy in 5 fractions. Chi-square analyses and multivariable logistic regression were used to investigate temporal, sociodemographic, and clinicopathologic predictors of HF-SRT receipt. Our cohort included 7,068 patients, among whom 5,243 (74%) received SF-SRS and 1,825 (26%) received HF-SRT. Median age was 63 years, and 51% of patients were female. The most common histology was NSCLC (87.2%). The proportion of patients receiving HF-SRT increased steadily from 20.3% in 2004 to 30.3% in 2014 (P<.001). Patients who received surgery at a distant site from the primary were more likely to undergo HF-SRT (35.3% versus 22.5%, P<.001). On multivariable analysis, predictors of increased utilization of HF-SRT included treatment year 2010-2014 versus 2004-2009 (odds ratio [OR] 1.14), colorectal versus NSCLC histology (OR 2.13), breast versus NSCLC histology (OR 1.72), surgery versus no surgery at distant site (OR 1.93), omission versus receipt of upfront chemotherapy (OR 1.49), and non-Northeast versus Northeast location (OR 1.39) (P<.05 for each). This analysis demonstrates steadily rising utilization of HF-SRT in the treatment of brain metastases nationally over the past decade. Adoption of HF-SRT also varied widely by histology, receipt of surgery or chemotherapy, and geographic location. Given the increased utilization of HF-SRT, further study is needed to investigate the underlying explanations for these differences and their impact on local control, distant intracranial control, and toxicity outcomes.